Hydraulic accumulators with biased fluid access values are commercially available. In the technical reference published by Mannesmann Rexroth GmbH “Der Hydraulictrainer” [Hydraulic Training Manual], Volume 1 on page 165, a bladder accumulator of this type is described. In the disclosed bladder accumulator, the valve arrangement is made as a seat valve. On the end edge of the connecting piece facing the fluid chamber, the stationary valve seat is a conical surface which interacts with the corresponding conical surface on the valve plate of the movable valve body. It is made similar to the control valves which are conventional in valve-controlled internal; combustion engines, i.e., the valve plate is located on a shaft which is guided in a valve guide as the valve support for the valve lifting motion extending between the open position and closed position. The valve guide is a component of the connecting piece.
The disadvantage of the conventional valve arrangement is the resulting high production costs due to the required expenditures for producing and machining of a plurality of individual parts as a result of this valve design. To ensure proper operation of the valve arrangement, the valve guide installed in the connecting piece must be made carefully with respect to production tolerances for both alignment and fit. Moreover, the corresponding machining of the conical surfaces which form the valve seat is necessary. This machinery likewise increases production costs, due at least to the valve plate of the valve body being produced by forging.
DE-A-199 06 800 discloses a hydraulic accumulator having a housing with an interior divided by a media separating element into two chambers. The first chamber is filled with a gas. The second chamber is filled with a liquid. In the hydraulic connection, a bottom valve with a closing body can be actuated by the media separation element in the form of the actuating plate of a spring bellows. The valve enables the second chamber to be filled with liquid and prevents the second chamber from being completely evacuated.
To both prevent damage of the bottom valve and also unintentional emergence of liquid, and thus, to ensure a considerable increase of operating reliability, the closing body, in this known approach, can be moved by the media separating element into a position in which the function of a hydraulic piston is performed. The closing body, on its side facing the separating plate of the spring bellows accumulator, has a spherical actuating part. In this respect, application of force with spot force peaks takes place by the media separating element on the closing body. The known valve body is completely guided in the connecting piece and requires a rubber-elastic sealing means for its sealing relative to the connecting piece on the outer periphery side. The rubber-elastic sealing means are basically subject to wear so that they must be replaced by new ones from time to time to ensure the operating reliability of the hydraulic accumulator.
FR 1 154 187 discloses a generic hydraulic accumulator, especially a bladder accumulator, with an accumulator housing and a separating element located therein and separating the accumulator housing interior into a gas chamber which borders a gas-side access and a fluid chamber which borders the fluid-side access. The fluid-side access has a fluid connecting piece with a valve support located on the connecting piece, a fluid passage and a plate-like valve body tapering toward the valve shaft on its side facing the valve support. The valve body is pretensioned into its open position clearing the fluid passage by an energy accumulator in the form of a compression spring, and can be moved into its closed position by the motion of the separating element. Also, the valve body projects in the open position into the fluid chamber. The valve body is an integral, especially a one-piece component, of the valve support guided to be able to move lengthwise along its outside periphery within the connecting piece. To limit the path of travel, the valve support is movably guided against a stop in the connecting piece. The stop is a sealing ring. In the known approach, the valve support has only one fluid passage which is otherwise penetrated by the energy accumulator in the form of the compression spring. In this respect, the known approach has a complex structure to increase production costs and accordingly, adversely affect operating reliability.
GB 2 104 964 discloses a generic hydraulic accumulator, especially a bladder accumulator comparable to the aforementioned French citation. The energy accumulator is a compression spring located underneath the valve body and extends between the valve body and the connecting piece. This known approach abandons a sealing ring. The piston-like valve body is securely held by a stop of the connecting piece. This approach has only one fluid passage in the valve body and is likewise complex and expensive to produce.
U.S. Pat. No. 4,335,751 discloses a membrane accumulator as a hydraulic accumulator in which in the connecting piece for carrying fluid has a fluid guiding part screwed in the connecting piece. The guiding part includes several fluid passages diametrically located relative to its lengthwise axis. On its top, the fluid guiding part has a plate-like guide surface which diverts the flow of fluid from the fluid passages to the fluid side of the hydraulic accumulator. The fluid guiding surface is an immovably integral component of the fluid guiding part fixed in the connecting piece of the membrane accumulator. The outside diameter of the guide surface is selected such that, from the side of the connecting piece, a screwing-in process is possible. The guide surface cannot extend over the edge-side boundary surfaces of the connecting piece toward the interior of the accumulator in the manner of a valve or the like. With the static arrangement of the fluid guiding part, based on the geometrical dimensions of the plate-like guiding surface, a valve function cannot be perceived, as in the above described approaches, even after corresponding modification.